It is known in the prior art of slidable window sash and frame construction to have vertical and horizontal sliding windows adapted to be pivoted out of the frame when desired. For tasks such as cleaning the window from within the building in which the window is installed, a pivoting window must be securely arrested from sliding at the pivot point to prevent balance assemblies associated with the window assembly from propelling the sash upwards. This can damage the sash and cause injury to the user.
Pivot mechanisms have included movable pins mounted on the edge of the sash which may be extended outwardly to engage holes in the frame about which the sash may be pivoted. U.S. Pat. No. 4,222,201 discloses a pivoting mechanism wherein a pair of spring biased pins are manually extended outward. Mating apertures in the tracks receive the pins, providing an axis of rotation. The sash may then be pivoted. After the window is pivoted back into the plane of the frame, the pins are retracted and secured in place by a screw to allow the sash to freely slide within the frame.
U.S. Pat. No. 5,058,321 discloses a mechanism wherein spring biased pivot pins are freed for selective extension into apertures formed in a frame by rotating said pins. The pins are retracted by rotation and secured in place by an arrangement of detents.
It is also known in the prior art to provide a pivoting arrangement which achieves automatic arresting of the sliding motion of a slider body in a track in response to the commencement of the pivoting of the window sash. U.S. Pat. No. 4,610,108 discloses such a device which incorporates a U-shaped spring member within a block member, wherein a pin extends from a window sash. A cam member is incorporated in the block and receives the pivot pin extending from the window sash. The cam member is rotatably engagable with the U-shaped spring member to lock the block in position upon pivoting the window sash. The cam member cams the U-shaped spring member wherein the outwardly opposed serrated tips are forced outwardly through slots in the block for penetration into the track wall by the serrated tips. Although simple to operate, experience has shown that a pivot arrangement of this type may not develop adequate arresting force. In addition, the serrated tips being engagable with and normal to the track wall, can become jammed in the wall after the window sash is returned to its slidable position. This configuration can also damage certain track constructions.
The present invention is provided to solve these and other problems.